In transportation vehicles such as automobiles, railroad vehicles, vessels, and aircrafts, noise and vibration are generated due to various kinds of factors.
For example, an engine or a motor that is an automobile power source generates noise and vibration while the engine or the motor is being driven. In addition, while an automobile travels, noise and vibration are generated in the vehicle body by an uneven road surface or the like. If such noise and vibration are directly transmitted into the vehicle body (cabin), occupants in the vehicle may be uncomfortable.
In view of this, techniques for suppressing such noise and vibration have been developed heretofore. For example, Patent Literature 1 discloses an asphalt sheet. The asphalt sheet of Patent Literature 1 may be used by being affixed on a floor panel of a vehicle as a measure against vibration and noise in the vehicle.
In other cases, for example, Patent Literature 2 and Patent Literature 3 respectively disclose a sound attenuating patch. The sound attenuating patch of each of Patent Literature 2 and Patent Literature 3 may be affixed on a main panel via an adhesive layer and attenuates noise and vibration.